JPH0321894A - Stage device - Google Patents

Abstract

PURPOSE:To improve the positioning accuracy by providing a movable member which can move relatively to a substrate, an arithmetic means which calculates the driving conditions of the movable member, and a control means which performs control according to the driving conditions found by the arithmetic means. CONSTITUTION:The stage device has a mechanism which moves a stage 1 in an X direction and a mechanism which moves a stage 2 in a Y direction. Four balancer weights 8 and 11, etc., are fitted corresponding to moving directions, etc., so as to cancel a reaction force and moment operating on a base board 3 as the stages 1 and 2 move. The stages 1 and 2 move on their tracks in the X and Y directions and the coordinate positions of the stages 1 and 2 are monitored by a position detector 40 and fed back to a stage controller 42. A computing element 4 finds the reaction force and moment operating on the base board 3 according to the positions and movement states of the stages 1 and 2 outputted by a controller 42 according to the detection signal from the detector 40. Consequently, the best driving conditions of the balancer weights 8, 11, etc., are calculated and a balancer controller 43 controls the movement of the balancer weights 8 and 11, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stage apparatus equipped with a vibration isolation mechanism, which is applied to, for example, a projection exposure apparatus.

[Background Art] In recent years, there has been an increasing demand for extremely high-precision positioning devices in various precision measuring devices, various devices related to semiconductor manufacturing, and the like. Usually, this type of positioning device has a stage movable in the X and Y directions. Further, in order to insulate vibrations from the ground, the base supporting the stage is held on the base of the apparatus by an elastic body or a buffer body.

Figure 7 is an example of a stage device equipped with a conventionally considered vibration-proof structure. In this conventional example, the stage 51 is
It is movably mounted on the upper orbit. In addition, the first base 5
2 is placed on a trajectory set on the second base 56 so that it can move in the opposite direction of the movement of the stage 51. Further, the second base 56 is supported by an elastic body 53 attached to the device top 54 on the base 55.

In this conventional example, when the stage 51 is moved, the stage 51
The structure is such that the first base 52 moves on the second base due to the reaction force caused by the movement of the base. That is, the structure is such that the reaction force is absorbed by the sliding of the first base 52, so that no vibration is generated in the first base 52.

[Problems to be Solved by the Invention] The stage apparatus described in the conventional example has some difficulty in being applied to a general stage apparatus used in a projection exposure apparatus or the like. In other words, in a stage device such as an XY stage that has two or more axes of movement, it is necessary to maintain the sliding surface in a strictly horizontal state and to provide a sliding mechanism that can slide in multiple directions corresponding to each axis of movement. be. This complicates the device structure and increases the weight of the device. Also,
When the stage moves on the first base, the reaction force generated on the first base simultaneously generates a moment that attempts to rotate the first base in a horizontal plane, and the sliding mechanism as described above absorbs this moment. Because it cannot be absorbed, it has not been possible to eliminate the vibrations of the equipment that occur when the stage moves or stops.

The present invention has been made to solve such conventional problems, and the ff of the stage increases as the stage moves.
An object of the present invention is to provide a stage device which is equipped with a mechanism that actively cancels out the reaction force generated on a substrate placed on the substrate, and which causes less vibration of the substrate as the stage moves.

[A Thousand Steps to Solve the Problem] A stage device according to the present invention is a stage device of a type in which the stage moves two-dimensionally on a horizontal plane of a base supported from a base by a vibration-proof structure. It includes a plurality of movable members of a predetermined mass that can move relative to the base.

In addition, when accelerating or decelerating the stage, the driving conditions for the movable members necessary to offset the force acting on the base are calculated based on the position of the stage with respect to the base and the state of movement (positive and negative acceleration, speed, etc.) Equipped with calculation means. Furthermore, in order to reduce vibrations of the base caused by acceleration and deceleration of the stage by moving the movable member, a control means is provided for controlling the movement of the movable member according to the drive condition determined by the calculation means.

[Function] In the stage device according to the present invention, the vibration isolation structure absorbs vibrations from the device base and suppresses transmission to the stage base. Furthermore, the stage is capable of two-dimensional movement on a trajectory set on a horizontal plane on this base.

Furthermore, a plurality of movement paths for movable members are installed on the base, corresponding to the moving direction of the stage, and each movable member of a predetermined mass moves on these movement paths to move relative to the base. This movable member is used to cancel the reaction force generated on the base as the stage moves. Therefore, the movable member has a mass corresponding to the weight of the stage. Further, the movement path of this is set at a position where movement of the movable member does not interfere with the original functions of the apparatus such as stage movement.

In the stage device according to the present invention, the calculation means calculates the drive conditions of the movable member necessary to offset the force acting on the base when accelerating or decelerating the stage, based on the position and movement state of the stage with respect to the base. calculate. Further, the control means controls the movement of the movable member according to the drive condition calculated by the calculation means. The reaction force or moment generated on the base by this movement of the movable member is controlled in the direction and magnitude to neutralize the reaction force or moment generated on the base due to acceleration or deceleration of the stage. As a result, vibrations of the base caused by acceleration or deceleration of the stage, such as vibrations when the stage stops, such as when positioning is completed in a projection exposure system, are almost completely absorbed. [Embodiments of the Invention] FIG. 1 is a schematic diagram showing a schematic configuration of a stage device according to a first embodiment of the present invention. The stage apparatus of this embodiment is a positioning XY stage suitable for use in a projection exposure apparatus, and is actually shown in FIG. 2(a). The mechanism and precepts are shown in (b). That is, it has a mechanism for moving the stage 1 in the X direction and a mechanism for moving the stage 2 in the Y direction. In addition, the balancer weights 8 to 11, which are two sets of movable members in the X direction and the Y direction, cancel the reaction force and moment acting on the base 3 as the stages 1 and 2 move.
Four of them are attached corresponding to the moving direction and position of stages 1 and 2. However, in FIG. 1, for the sake of explanation, the movement of the stage l in the X direction and the balancer weight 11 on the front side are shown.
Only shown. The stage 2 moves in the y direction on a track (guide rail) set on a horizontal plane on the base 3. Also, stage 1
moves in the X direction on a trajectory set on the horizontal plane above stage z. The base 3 is supported on a device base 21 installed on a floor surface 45 by an elastic body 20 for vibration isolation.
Note that stages 1 and 2 move on base 3 based on No. 3 from stage controller 42. In addition, the coordinate positions of stages 1 and 2 at this time are two mirrors fixed to the sides of stage 1 along the The position is monitored by a position detector 40 composed of two interferometers, and fed back to the stage controller 42.

The balancer weights 8 to 11 are supported by feed screws 12 to 15 provided on the side surface of the base 3, and are supported by the balancer controller 43.
Relative movement (linear movement) with respect to the base 3 is performed based on signals from. Note that the masses of the balancer weights 8 to 11 are determined according to the masses of the stages 1 and 2. For this reason, it is desirable to consider the space around the stage and use a high-density material such as lead.

Arithmetic unit 41 is a stage controller 42 outputs based on a detection signal from position detector 40! , 2 and the movement state (positive and negative acceleration, speed, etc.), the reaction force and moment acting on the base 3 are determined, and based on this, the optimal driving conditions for the balance weights 8 to 11 are calculated. According to this driving condition, the balancer controller 43 controls the movement of the balancer weights 8 to 11. The reaction force acting on the base 3 as the stages 1 and 2 move is the combination of the acceleration and mass of the stages 1 and 2. It is the inertial force expressed as the product.Strictly speaking, in the y direction, stage 1
, 2, and the weight of only stage 1 in the x direction. Further, the rotational force acting on the base 3 at this time is a moment expressed by the product of the distance between the point of force of the stages 1 and 2 on the base ffl3 and the center of gravity of the base 3 and the reaction force.

In this embodiment, by moving stages 1 and 2, the base 3
These reaction forces and moments acting on the base plate 3 must be simultaneously canceled by the reaction forces and moments acting on the base 3 due to the movement of the balancer weights 8 to 11. For example, when stage 1 moves in the X direction as shown by the arrow in Figure 1, the two balancer weights 9 and 1l are accelerated and decelerated in the opposite direction to the movement of stage 1, canceling out the reaction force. It will be done.

At the same time, the allocation of acceleration to the balancer weights 9 and 11 is determined based on the positional relationship of the stages 1 and 2 with respect to the center of gravity of the base 3 at this time. If this is insufficient, for example, the accelerations for moving the balancer weights 8 and 12 in opposite directions are determined. Balancer weight 8 = 1 according to this driving condition
The movement of 1 also cancels out the moment.

However, in this embodiment, which is an XY stage for positioning in a projection exposure apparatus, the biggest problem is the occurrence of vibration when the stages 1 and 2 are stopped, which has a serious effect on positioning accuracy. So, the stage! , completely cancel out the reaction force and moment generated in the base 3 during deceleration and stop of step 2 as described above, and use the other periods of acceleration and constant movement to return to the origin of balance weight 8 to 1l. Appropriate resets such as recovery are performed. Further, the calculator 41 may incorporate the stages 1 and 2 positions into the drive conditions of the balancer weights 8 to 11 according to the position information from the position detector 40, but in this embodiment, the stage 1 and 2 movement program ( (including design target position information for positioning stages 1 and 2), the drive conditions for balancer weights 8 to 1l are automatically calculated.

In the configurations shown in Figures 1 and 2 up to this point, 1 and 2 are stages that move in the X direction and Y direction, respectively, and 4 and 6.
is the feed screw for driving each stage 1 and 2,
5 and 7 are motors for driving the feed screws 4 and 6, respectively. Moreover, 16-19 are motors for driving the feed screws 12-15.

Now, in the XY stage of this embodiment, as shown in FIG. 3(a), the
When the reaction force F acts on the base 3, the balancer weights 9 and 10 are driven (accelerated) in the directions of arrows Ay and Ax, respectively. As a result, the balancer weights 9 and 10 generate reaction forces F9 and FIO on the base 3, respectively, to cancel out the reaction force F3. Reaction forces F3, F9, F1 at this time
0 relationship is shown in Figure 3(b). Reaction force F3, F9, FI
The resultant force of O becomes zero, and the base 3 remains stationary and no vibration occurs.

The above action can be handled by combining the movements of the balance weights 8 to 11 and their drive amounts (accelerations) regardless of the acceleration or deceleration of stages 1 and 2 at any position on the base 3. , even if the acceleration of stages 1 and 2 changes while they are moving, balancer weights 8 to 1
By changing the drive acceleration of 1, flexible responses are possible. Next, the center of gravity of stages 1 and 2 is set relative to the base 3 as shown in Figure 5 (
The control algorithm for the balancer weights 8 to 11 in this embodiment will be explained with reference to FIG. 6, taking as an example the case where the movement shown in the graph of a) is performed.

In Fig. 5(a), the centers of gravity of stages 1 and 2 move with constant acceleration from a resting state (time t = 0) until they reach a predetermined speed v0, and when they reach a predetermined speed Vo at time t, they move at a constant speed from there. It continues to move, and then decelerates with uniform acceleration from time t2 and stops at time t3.The accelerations of the centers of gravity of stages 1 and 2 during this acceleration period and deceleration period are as shown in Figure 5 (b). are assumed to be constant at ±a., respectively.Therefore, after confirming the current position and target position of stages 1 and 2 (step 100),
Based on the acceleration of stages 1 and 2 (here, the acceleration map shown in FIG. 5(b)), the force generated as the stages 1 and 2 move is calculated (step 101). That is, this acceleration a. Therefore, the reaction force F on the base 3 is given by the following formula
acts. F=MXao M: Stage 1, 2 mass (However, if only one stage 1 moves, M
: Stage 1 mass) Here, for example, stage! , 2 passes over the center of gravity of the base 3, the reaction force F acting on the base 3 is:
This is a force that attempts to move the center of gravity of the base 3 in the opposite direction to the direction of movement of the center of gravity of stages 1 and 2, and no moment is generated that rotates the base i3 within the movement plane. Therefore, at this time, the angle between the moving direction of the center of gravity of stages 1 and 2 and the X axis is θ
Then, in order to cancel the reaction force F, balancer weights 9 and 11 in the X-axis direction and balancer weights 8 and 1 in the Y-axis direction are used.
The reaction force FxFy that should be applied to the base 3 by driving 0 is simply given by the following equation.

Balancer weights 9, 11 in X@ direction FX = MXa, Xcos θ Balancer weights 8, 10 in Y@ direction F, = Mxa o Xs in θ As a result, the above reaction forces F, F, and balancer weights 8 to 1
Based on the mass of balance weights 1 to 1, drive conditions of balance weights 8 to 11, that is, drive acceleration are determined (step 102).
, this calculation result is output to the balancer controller 43.

Now, in the control algorithm of this embodiment, the accelerations of balancer weights 8 to 11 are determined as described above (step 10).
2) After 1,, it is determined whether the moving direction of the center of gravity of stages 1 and 2 passes over the center of gravity of the base 3 (step 103).
. As a result of this judgment, the direction of movement of the center of gravity of stages 1 and 2 is
If it does not pass over the center of gravity of the base 3, the reaction force F acting on the base 3 is a force that attempts to move the center of gravity of the base 3 in the opposite direction to the movement of the center of gravity of stages 1 and 2, and at the same time moves the center of gravity of the base 3. It also generates a moment that tends to rotate within the plane. Therefore, the moment generated in the base 3 as the stage moves is determined (step 104), and the driving acceleration of the balancer weights 8 to 11 is calculated from this moment as a driving condition (step 105). Then, the drive conditions for canceling this moment are output to the balancer controller 43 in conjunction with the above-mentioned drive conditions (step 106), and the balancer weights 8 to 11 are set to the stage! , 2 are driven almost simultaneously with the acceleration/deceleration of stages 1 and 2 (step 107).The driving conditions at this time are that the center of gravity of stages 1 and 2 is located on the X or Y axis on the symmetric side across the center of gravity of base 3. The balancer weights 8 to 11 may be driven with acceleration in the same direction as the moving direction of the centers of gravity of stages 1 and 2. The force that cancels the action as a moment is the vector force generated by the movement of the stage. , if the radius vector between the centers of gravity of stages 1 and 2 and the center of gravity of base 3 is r, then it is given by the following equation. r=l F, Ixlr. lxcos θ As a result, the reaction force F generated on the base 3 as the stage moves
and Momen 1 have been canceled,
It becomes possible to significantly reduce the occurrence of vibrations in the base 3.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a perspective view showing the structure of the parallax weights 22 to 25 attached to the side surface of the base 3 in the second embodiment of the present invention. Here, the parts other than the balancer weights 22 to 25 have the same structure as the first embodiment. Further, the balancer weights 23 and 24 are attached to the side surface of the base 3 opposite to the balancer weights 25 and 22, respectively.

Balancer weight 2 which is a movable member in the second embodiment
2 to 25 are eccentric loads rotatably attached to the base 3. Furthermore, the acceleration and moment accompanying the movement of the stage 3 are canceled out by the angular movement of this eccentric load. Moreover, the rotation center of each balancer weight 22-25 is parallel to the X-axis and the Y-axis.

These balance weights 22 to 25 are controlled according to a flowchart in FIG. 6 in which the accelerations of balancer weights 8 to 11 are replaced with angular accelerations of balancer weights 22 to 25. In this embodiment, since the balancer weight rotates, the direction of reaction force generation is reversed every 1/2 rotation. Therefore, it is sufficient to rotate in only one direction. In addition, in the case of such a balancer weight, it is possible to suppress vertical shaking of the sides of the base plate 3.

As described above, according to both embodiments, it is possible to eliminate the vibration of the base 3 caused by the movement of the stages 1 and 2, thereby improving the positioning accuracy and efficiency (time) of the stages 1 and 2. Further, the influence on things on the stages 1 and 2, such as displacement of the wafer, can be minimized.

In addition, as in both of these embodiments, the movement path of the movable member is
By setting the movable member at a position where the movement of the movable member does not interfere with the original functions of the apparatus such as stage movement, the degree of freedom in stage design increases and the overall stage apparatus can be made smaller.

[Effects of the Invention] In the stage device according to the present invention, the force acting on the base when accelerating or decelerating the stage is offset by the movement of the movable member, so vibrations of the base caused by acceleration or deceleration of the stage, such as projection Vibration when the stage is stopped, such as when positioning in the exposure apparatus is completed, is almost absorbed. This improves the positioning accuracy of the stage (
FIG. 1 is a schematic diagram showing the general configuration of an XY stage according to a first embodiment of the present invention.

FIGS. 2(a) and 2(b) are a 2nd and 4th perspective view and a plan view, respectively, showing the configuration of the XY stage of the first embodiment of the present invention.

FIG. 3(a) and FIG. 3(b) are a schematic plan view and a schematic diagram of vector force, respectively, in the XY stage of the first embodiment of the present invention.

FIG. 4 is a perspective view showing the configuration of an XY stage according to a second embodiment of the present invention.

FIG. 5(a) and FIG. 5(b) are a diagram of a change in velocity over time and a diagram of a change in acceleration over time, respectively, showing the moving state of the stage in the XY stage of the first embodiment of the present invention. It is.

FIG. 6 shows the XY stage node of the first embodiment of the present invention. FIG. 3 is a flowchart diagram illustrating control.

FIG. 7 is a schematic diagram showing the general configuration of a conventional stage device.

[Explanation of symbols of main parts] 1...Stage 3...Foundation 11...
Balancer weight 20...Elastic body 40...Position detector 41...Calculator 43...Balancer controller

Claims (1)

[Scope of Claim] A stage device having a stage provided on a base of a vibration-proof structure and movable two-dimensionally in a horizontal plane, comprising: a plurality of stages having a predetermined mass that are movable relative to the base; a movable member; and a drive condition for the movable member necessary to offset the force acting on the base when accelerating or decelerating the stage is calculated based on the position and movement state of the stage with respect to the base. comprising a calculation means and a control means for controlling the movement of the movable member according to the calculated drive condition, the vibration of the base generated by acceleration and deceleration of the stage being reduced by the movement of the movable member. A stage device characterized in that the stage device is configured to